The Joker does not have one Wikipedia URL. He has several, and the right one depends on what you are after. If you want the DC villain, the address is en.wikipedia.org/wiki/Joker_(character). If you want the 2019 Joaquin Phoenix film, it is en.wikipedia.org/wiki/Joker_(2019_film). And the bare address en.wikipedia.org/wiki/Joker drops you on a disambiguation page that lists both of those plus the playing card, the 2008 Batman episode, and a handful of albums and songs that borrowed the name.

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That last page is the one most people land on by accident. They type the obvious thing, get a list, and assume Wikipedia is being difficult. It is not. It is just refusing to guess.

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How the address is put together

Every Wikipedia article URL follows the same skeleton. A language subdomain comes first, then the project domain, then the path /wiki/, then the page title. So "en" means the English edition, and the title follows in the path. Spaces become underscores, so a two-word title reads with an underscore between the words. Parentheses stay as they are, which is why the character page keeps its (character) suffix intact.

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Punctuation that has meaning in a URL gets percent-encoded. Apostrophes show up as %27, and a title with a slash in it will be escaped so the path does not break in two. The first letter of a title is treated as uppercase no matter how you type it, but everything after that is case sensitive.

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Why the parentheses exist

Wikipedia adds a parenthetical qualifier when two subjects would otherwise claim the same title. The DC character came first in the public imagination, but the word "Joker" also belongs to a card, a film, and a stack of other entries. Rather than let one win, editors keep the plain title as a disambiguation hub and move the specific topics to qualified names. The same logic gives you Joker (character) and Joker (2019 film) living side by side without fighting.

Versions of the same page

There are a few variants worth knowing about.

• Mobile: swap the en for en.m and you get the phone-friendly layout.
• Other languages: replace the language code, and you get that edition's article on the same subject, assuming one exists.
• Permanent: a page address with an oldid parameter points at one frozen revision instead of the ever-changing current one.
• Legacy: the older index.php?title= format still works and redirects to the clean path.

Redirects fill the gaps. Type a close variant of a title and you usually get forwarded to the real article without noticing.

Finding it without typing a URL

I rarely type these addresses out. The search box on Wikipedia is faster, and it is forgiving about missing parentheses. Search for the name, scan the results, and click the entry that matches what you meant. Then copy the address from the browser bar if you need it for something else. That way you never have to remember whether it is a qualifier, an underscore, or a redirect.